Question

在一个小部件中是否可以有多个StreamBuilder？

我已经关注了小部件：

class BuilderLoading extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    TenderApiProvider apiProv = Provider.of<TenderApiProvider>(context);
    // apiProv.getToken();    
    return StreamBuilder<ApiKeyLoadingState>(
        stream: apiProv.streamApiKeyController.stream, // here
        builder: (BuildContext context, AsyncSnapshot<ApiKeyLoadingState> snapshot)
        {
          switch (apiProv.apiKeyLoadingState) {               
            case ApiKeyLoadingState.Progress:
                return Text("Retreiving key");
            case ApiKeyLoadingState.Done:
                return HomePage();
            case ApiKeyLoadingState.Error:
                return Text("Key Got Error");
              break;
            default:
              return Text("Unknown");
          }

        }

    );

  }
}

我在这里检查streamApiKeyController。但我想在此窗口小部件中显示另一个流的状态。喜欢： streamApiKeyController，streamRegionsLoadingController，streamIndustryLoadingController。我该怎么办？

我的意思是：

return (
builder: (BuildContext context, AsyncSnapshot<ApiKeyLoadingState> snapshot)
{
   // ... streamApiKeyController

}

builder: (BuildContext context, AsyncSnapshot<regionsLoadingState> snapshot)
{
   // ... streamRegionsLoadingController
}
);

要获取列表：

领取钥匙

RegionsLoading

Answer 1

您可以像这样嵌套StreamBuilder，只需从第一个构建器的第二个流中返回另一个StreamBuilder即可：

class BuilderLoading extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    TenderApiProvider apiProv = Provider.of<TenderApiProvider>(context);
    // apiProv.getToken();    
    return StreamBuilder<ApiKeyLoadingState>(
        stream: apiProv.streamApiKeyController.stream, // here
        builder: (BuildContext context, AsyncSnapshot<ApiKeyLoadingState> apiKeySnapshot)
        {
          return StreamBuilder<regionsLoadingState>(
            stream: streamRegionsLoadingController,
            builder: (BuildContext context, AsyncSnaptshot<regionsLoadingState> regioSnapshot)
            {
               if (!regioSnapshot.hasData) return Text("Regiodata not loaded");
               switch (apiProv.apiKeyLoadingState) {               
                 case ApiKeyLoadingState.Progress:
                  return Text("Retreiving key");
                 case ApiKeyLoadingState.Done:
                  return HomePage();
                 case ApiKeyLoadingState.Error:
                   return Text("Key Got Error");
                 default:
                   return Text("Unknown");
               }
            } 
          );
        }

    );

  }
}

当然，您需要在内部构建器中定义自己的自定义逻辑，我只是出于演示目的添加了一些“虚拟”逻辑。

Answer 2

您可以嵌套StreamBuilders：

class BuilderLoading extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    TenderApiProvider apiProv = Provider.of<TenderApiProvider>(context);
    // apiProv.getToken();    
    return StreamBuilder<ApiKeyLoadingState>(
        stream: apiProv.streamApiKeyController.stream, 
        builder: (BuildContext context, AsyncSnapshot<ApiKeyLoadingState> snapshotAPIKey){
              return StreamBuilder<ApiKeyLoadingState>(
              stream: streamRegionsLoadingController,
              builder: (BuildContext context, AsyncSnapshot<ApiKeyLoadingState> snapshotRegionsLoading)
            { 
            /// Do Stuff here
          }
         );
        }
     );
  }
}

一个小部件中可以有多个StreamBuilder吗？

2 个答案: